The present invention relates to a newly structured magnetic recording head and a magnetic recording method utilizing the magnetic recording head.
Recently, a longitudinal magnetic recording method has been employed as a magnetic recording method. In the longitudinal magnetic recording method, the magnetizations relating to signals to be recorded are directed in parallel in the plane of a recording medium. However, the instability in the signals becomes remarkable due to heat fluctuation as the recording density becomes high so that the longitudinal magnetic recording method is substituted with a perpendicular magnetic recording method because the longitudinal magnetic recording method can maintain the signals stably. With the perpendicular magnetic recording method, since the magnetizations relating to the signals are directed perpendicular to the plane of the recording medium, a perpendicular recording magnetic head is required so as to realize the perpendicular magnetic recording method.
FIG. 1 is a structural view schematically showing a magnetic recording method using a conventional perpendicular magnetic recording head. In FIG. 1, a perpendicular magnetic recording head (hereinafter, often abbreviated as a “recording head”) 10 includes a main magnetic pole 11 and a pair of sub magnetic poles 12 which are arranged by a predetermined gap width. The rear end of the main magnetic pole 11 is magnetically connected with one of the sub magnetic poles 12. A coil 13 is wound around the main magnetic pole 11 so as to generate a writing magnetic field. A magnetic recording medium 20 is configured such that a recording layer 21 and a soft magnetic underlayer 22 are arranged via a non-magnetic intermediate layer 23.
The spacer layer magnetically divide the pinned layer and the free layer so that the magnetization of the free layer can be rotated independently from the magnetization of the pinned layer.
In writing, a writing current is flowed in the coil 13 to generate the current magnetic field at the main magnetic pole As a result, the magnetizations of the main pole 11 are aligned along the direction of the writing current to generate the leaked magnetic field as a writing magnetic field. The writing magnetic field is applied to the magnetic recording medium 20 so as to penetrate through the magnetic recording medium 20. In this case, the bit information of the recording layer 21 is rewritten so that the writing magnetic field is circulated toward the sub magnetic poles 12 via the soft magnetic underlayer 22.
FIGS. 2 and 3 are explanatory views for the writing process of the recording head shown in FIG. 1. As shown in FIG. 2, when the current magnetic field is applied to the main magnetic pole 11 from the coil 13, the magnetization Ms of the main magnetic pole 11 is directed downward so that the writing process for the recording layer 21 of the magnetic recording medium 20 can be carried out by the leaked magnetic field from the magnetization Ms. On the other hand, as shown in FIG. 3, the current magnetic field is not applied to the main magnetic pole 11 from the coil 13 under the non-writing process, but the remnant magnetization MR occurs in the main magnetic pole 11 so as to realize the rewriting process of the bit information in the area of recording layer 21 located under the main magnetic pole 11. Such a rewriting process is called as a “Pole erasure”.
In order to prevent the Pole erasure, such an attempt as devising the shape of the main magnetic pole 11 is made, but the writing efficiency can not be enhanced sufficiently and the Pole erasure can not be suppressed sufficiently because the writing efficiency is traded off with the Pole erasure. At present, the writing efficiency and the Pole erasure are appropriately controlled in view of the trade-off relation as occasion demands.
Recently, in view of the above problem, anew type magnetic recording head is proposed. In the magnetic recording head, main magnetic pole-magnetization fixing portions 24 made of antiferromagnetic material are disposed at both sides of the main magnetic pole 11 respectively so as to generate the magnetization toward the track width direction of the magnetic recording medium in the main magnetic pole 11 through the exchange coupling between the main magnetic pole 11 and the fixing portions 24 and then, conduct the writing process using the leaked magnetic field from the magnetization (Reference 1). FIGS. 4 and 5 show the magnetic recording head as described above. FIG. 4 shows the state of the magnetic recording head under the standby state, that is, not-writing condition. In this case, the magnetization of the main magnetic pole 11 becomes parallel to the surface of the recording layer 21 through the exchange coupling between the main magnetic pole 11 and the fixing portions 24. FIG. 5 shows the state of the magnetic recording head under the writing condition. In this case, the magnetization of the main magnetic pole 11 becomes perpendicular to the recording layer 21 along the current magnetic field Bs by the current flowed in the coil 13. In this case, the Pole erasure can be suppressed, but the writing efficiency is reduced because the magnetization of the main magnetic pole is unlikely to be directed perpendicular to the surface of the recording layer.
[Reference 1] JP-A 2006-190397 (KOKAI)
An aspect of the present invention relates to a magnetic recording head including: a main magnetic pole containing a ferromagnetic layer; a main magnetic pole-magnetization fixing portion containing an antiferromagnetic layer in contact with at least one side surface of the main magnetic pole; a heater for heating at least the main magnetic pole so that a magnetic interaction between the main magnetic pole and the main magnetic pole-magnetization fixing portion can be decreased; and a magnetic field generator for generating a magnetic field so as to direct a magnetization of the main magnetic pole in one direction.
Another aspect of the present invention relates to a magnetic recording method using a magnetic recording head including; a main magnetic pole containing a ferromagnetic layer; a main magnetic pole-magnetization fixing portion containing an antiferromagnetic layer in contact with at least one side surface of the main magnetic pole; a heater for the main magnetic pole; and a magnetic field generator for generating a magnetic field so as to direct a magnetization of the main magnetic pole in one direction, including: heating, in writing, the main magnetic pole with the heater so that a magnetic interaction between the main magnetic pole and the main magnetic pole-magnetization fixing portion can be decreased; and generating, in the writing, the magnetic field with the magnetic generator so that the magnetization of the main magnetic pole can be directed perpendicular to a surface of a recording medium by the magnetic field.